Abstract

Fragmented habitats exhibit distinctive patterns of
species richness and species composition. They often
exhibit patterns of pronounced nestedness, wherein
the species present in comparatively depauperate locations
represent statistically proper subsets of those
present in locations that are richer in species. The
current study has been conducted on the freshwater
fishes of Sharavathi River, considering 41 stream and
reservoir sites with 261 sampling events to understand
the nestedness pattern in fish communities. Of the 64
fish species collected, 39 are from the reservoir and 33
from the stream islands. For the species of the stream
islands, including the reservoir fishes in the stream,
the nestedness index, T was 8.27°C, while species
exclusive to stream islands had T = 10.5°C. In contrast,
in species that are common to both stream islands and the reservoir, T was 0.37°C. Relatively higher T in the exclusive stream species composition implies that they are highly depauperated due to fragmentation in the streams and its negative influence on the stream fish communities.